Edward Judd, who has died aged 76, had a long career as a film and television actor. He appeared in supporting roles in dozens of films, including Carry on Sergeant (1958) and Sink the Bismarck! (1960), and enjoyed a brief moment in the spotlight as the star of the sci-fi thriller The Day the Earth Caught Fire (1961).

Despite his good looks and intensity, he was unable to build on the film's international success. Apart from The Day the Earth Caught Fire, he is probably best known for the "Think once, think twice, think bike" TV commercials of the mid-1970s and a stint on Coronation Street (1982), playing Elsie Tanner's boyfriend, Geoff Siddall, who turned out to be a conman.

Judd had drink problems, disappeared from view and was reputedly homeless for a while. It was even reported that he was dead in 2005, on the sleeve notes for the DVD release of the sci-film Island of Terror (1966). There was considerable debate online. The author of the sleeve notes said notice of his death had appeared in the Equity journal. Eventually someone confirmed he was living in London.

Born in Shanghai, to British parents, he began acting in Britain in his teens. He laboured for years, often without even getting his name on the credits, before he got his big break in The Day the Earth Caught Fire, playing the Daily Express reporter who discovers that nuclear testing has knocked the Earth out of its orbit and it is hurtling towards the Sun. The film had a gritty realism, an intelligent script and a famous "open" ending. The superpowers attempt to knock the Earth back into its original orbit, Judd dictates a final story on the fate of mankind and two alternative front pages are prepared announcing "World doomed" and "World saved".

Judd also starred in the H G Wells adaptation First Men in the Moon (1964), but it lacked the resonance and contemporary relevance of The Day the Earth Caught Fire.

Island of Terror, in which he appeared with Peter Cushing, represented a descent into more routine horror material, in which islanders are menaced by tentacled monsters.

In the 1970s and 1980s, Judd worked regularly on television, with appearances on The New Avengers (1976), Flambards (1979) and The Hound of the Baskervilles (1983), with Ian Richardson and Eleanor Bron.